Burglar-alarm trap



s. B. Hr-:s's

BURGLAR ALARM TRAP Filed nec. 19, 1925 Jan. 22, 1929.

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Patented Jan. 22, 1929.

g UNITED STATES YSIMON B. HESS, F NEW YORK, N. Y.

BURGLAR-ALARM TRAP.

Application led December 19, 1925. Serial No. 76,405.

rlhis invention relates to electrically operated alarm signals, particularly to what are known as burglar alarm traps.

Itis customary to provide in burglar alarm systems an alarm circuit and a controlling circuit therefor, the latter including a springpressed switch member operated by a trip cord. The trip cord is secured at one end to thc switch member, normally holding the switch in neutral position, while the other end of the trip cord is fastened to a door or window, or positioned so an intruder will brush against it. Then the cord is pulled or broken the switch member moves to change thecondition of the controlling circuit and thereby causes actuation of the alarm. lith this arrangement, if the owner ofthe premises wishes to keep 'the alarm inoperative during the day time, he can leave the electrical circuits in operative condition and hold the switch member in neutral position by tying the cord to a convenient object. The objection to this procedure is that he may leave the premises in the evening forgetting to connect the cord in'its operative position.

One of the objects of this invention is to provide an arrangement of parts in the supervising circuit in which the cord or wire which holds the circuit cont-roller in normal position is itself a conductor and is a part of the supervising circuit. rlhe circuit is so arranged as to render it necessary to place the trip wire in protective posit-ion before the alarm can be set.v

A further object of the invention is to detachably 4connect the trip wire to the pivotcd switch member in such a way that contactvwith the wire'will move the pivotcd member in one direction to a sutticient extent to change the normal condition of the super vising circuit and cause operation of the alarm. Simultaneously the wire is freed lfrom its connection with the switch member, whereupon, by the operation of a spring connected to the pivoted member, the latter is moved to and held in such a position with relation to the circuit of which it forms a part, that the controlling circuit remains in condition to cause or permit the continuance of the alarm.

lVhile I have disclosed a. preferred embodiment of the invention for purposes of illustration, it should be understood that the structure may be modified in various ways without departure from the true spirit and scope of the invention, as hereinafter deiined and claimed. I

In the drawings Fig. 1 is a. diagrammatic view showing the electrical circuits.

Fig. 2 is a plan view of the controlling switch.

Fig. 3 is a side elevation of the switch box, the front side having been removed.

Fig. et is a detail view showing the mounting of the switch member.

Referring more particularly to the drawings, there is shown at 5 a base carrying a boxlike structure having atop 6. A switch member 7 is pivotally carried on the under side of the top by a bolt 8. A conductor strip 9 is held in electrical Contact with the switch member by bolt S, as shown in Fig. t, and extends to a point outside the box where it is provided with a binding post 10. A conductor strip 11 extends across the base at the front of the box and carries binding posts 12 and 13 outside the box. Contact members 14 and 15 are mounted on conductor 11 in such a manner as to contact with the switch member 7 at certain times.

The switch member is biased by a spring 1G toward stop 17 mounted on top 6. The outer end of the switch member is notched, as indicated at 18, the outer ends of the notch being curved as shown. The trip wire 20 passes over a pulley 21 mounted on the box and carries a ring 19 passed over one prong of the notched end of the switch member. The opposite end of the trip wire is secured to a pointed contact member 22 which is frictionally gripped between two curved spring members 23 mounted on a base 24.

The members 23 are connected to battery 25 by a. conductor 26, the battery being grounded at 27 and a wire 28 connecting the opposite side of battery 25 to the binding post 13. A conductor 29 connects binding post 12 to an alarm bell 30, the bell being connected to one side of a battery 33 by conductor 35. The opposite side of battery 33 is connected to contact 36 by a conductor 34.

Y A conductor 37 connects the binding post 10 to both units 38 and 39 of an electromagnetand a conductor 40 connects the electromagnet to the contact 41. A conductor 4t2 connects with conductor 37 between the units of the electromagnet and is grounded at 43.

A pivoted armature 32 is mounted in op erative relation to the electromagnet and is free to move against either of the contacts 36 or 41. A wire 31 connects the armature to conductor 29.

' The operation of the device is as follows:

lVhen the trip wire 2O is placed in protective position with Contact member 22 gripped between spring contacts 23, the switch member 7 `will be held in a neutral position between contacts le and 15, as shown in Figs. l and 2. rlhe current then iiows through the supervisory circuit in the following manner; Jfrom battery through conductors 23, 1l, 29, 3l to armature 32, thence through contact 4l conductors 40, 37, switch member 7, trip wire20, contact members 23, lconductor 2G Ybach to the battery 25. rlhis current enorgizes the electromagnet which retains the armature, thereby maintainingv the armature in raised position, rlhe supervisory circuit is then in protective position and the alarm circuit is inoperative.

lt an intruder should brush against the trip wire 2O without disconnecting its ends, the switch member 7 would beinoved against either o the contacts le or l5, thereby short# circuiting the' current trom conductor 2S directly int-o switch member 7 and thence via,Y the trip wire bach to the battery. rllhis would throu h conductors i 32`l 3l and 29 to the bell and thence throughconductor 35 bachl to the battery.

lttrip wire 2O should be broken or disconnected at either end in such a violent inanner as to cause theswitch member 7 to iii-st move against contact lei before the circuit through wire 20 is broken, then the electromagnet will be entirely shortecircuited as outlined above, putting the alarm circuit into operation. i'ter the switch member is released frein the control ot the trip wire, the spring 16 will move the switch member into engagement with contactl (Fig. l) and current williiow only through the unit 33, which is not strong enough to littarmature 32, and Ahence' the alarmwill continue to operate.

It the intruder should break or remove the trip wire, the switch member would be moved by spring i6 against Contact l5. ln this po-Y sition the current Vwould iiow through unit 33 ot the electro-inagnet as follows; from battery 25, through conductors, 2S, ll, 7, 37

yto raise the armature to unit- 38, thence through conductor 42 to ground 43, to ground 27 and bach to battery 25. At the same time current would Yiiow through unit 39 as follows: from battery 25, through conductors 2S, l1, 29, 3l, 32 and i0 to unit 39,'thence via wire 42 to ground 43, to ground 27 to battery 25. The current is therefore passing through unit 33 in a direction opposite to the current passing through unit- 39. These units will therefore be oppositely polarized, one attracting and the other regelling armature 32, and the armature will thereioredrop, completing the alarm circuit.

The provision oi this. type circuit insures Vthe proper setting ot the trip wire, .since a circuit through the trip wire is necessary to place the supervisory circuit in protective condition. rllhis is true because it is only when current is flowing through the trip wire that both units ot the electro-n'iagnet are energized to attract the armature 32, and the combined attraction oi both units is needed 32, thereby putting the supervisory circuit in protective condition.

l claim A burglar alarm system comprising an alarm circuit, an armature forming part oi said alarm circuit, a pair of coils 'for holding said armature in position to open the alarm circuit, a pivoted switch arm, a conductor connecting the switch arm to both of the coils in series, a Contact on each side oit the' switch arm, a secondlconductor connecting i785 the contacts to each other, a third conductor i connecting the second conductor to the arinaturc, Va source of electrical current, a iourthi in testimony whereof affix my signature. y

einen n. nnss. 

